1. Field of the Invention
The present invention relates to a combination hole puncher and reinforcer by means of which holes are punched in sheets of material, such as paper, and concurrently reinforced with flat, annular rings around the holes.
2. Description of the Prior Art
In offices throughout the world hole punching devices have been utilized for many years so as to punch holes in sheets of paper, and sometimes plastic sheets, to allow those sheets to be secured in files. Sheets of paper are often punched at the top with a pair of holes that allow them to be secured at the top to files using pronged fasteners. Other types of hole punchers are used to punch holes in papers and other sheets of material along the sides to allow them to be secured in ring binders.
A problem that has persisted through the years is that considerable stress is often applied to the structure of papers fastened in files in the area immediately surrounding the punched holes. The papers then tear through the short distance of material between the holes and the edges of the sheets of paper near which they are formed. When this occurs the sheets will no longer remain in the file.
One system for remedying this situation that has been available for many years is the use of flat, annular reinforcing rings that may secured to the areas surrounding the punched holes. These reinforcing rings are typically formed of a material of greater strength than the paper in which the holes are punched. The reinforcing rings are coated with either a moisture-sensitive or pressure-sensitive adhesive and are applied to the sheet of paper or other material once the holes have been punched.
The principal problem with this prior arrangement is that it has historically been performed manually. The task of reinforcing punched holes in the hundreds, and even thousands, of sheets papers that are secured in files by the manual application of such reinforcing rings is often so labor intensive as to be impractical. Consequently, this system of reinforcement, while used to some extent, is not prevalent.
Various hole puncher and reinforcer devices have been created in attempts to provide alternative way of reinforcing the structure of sheets of paper around punched holes therein. Numerous machines have been fabricated that draw segments of adhesive tape from rolls and secure them to sheets of paper or plastic contemporaneously with the perforation of those sheets. When such devices operate properly, the sheets of paper are provided with short sections of tape at the edges of the papers in which the holes are formed. Holes are punched through both the segments of tape and the underlying paper or other sheet material.
These tape reinforcement devices also have, to a large extent, proved impractical. The feed mechanisms for the tape often jam and the tape often adheres to parts of the punching machines as it is fed toward the location on the sheets of paper at which it is to be applied.
Another problem with systems employing adhesive tape to reinforce the areas about punched holes is that the punch mechanism must penetrate not only the paper in which the fastening apertures are to be formed, but also the tape as well. Since the tape is coated with pressure-sensitive adhesive, articles of adhesive are transferred to the punch mechanism. This creates a certain gumminess in the punch mechanism that reduces the effectiveness of the punch in creating apertures. Also a build-up of adhesive in the punch mechanism contributes to the fouling of the tape as the tape is fed into position to be pressed against the paper.
The present invention is a hole puncher and reinforcer device that automatically applies a reinforcement about a hole that is punched in a sheet of material, but which avoids the use of adhesive tape drawn from a roll for this purpose. As a consequence, the hole punching and reinforcing device of the present invention avoids the problem of fouling of a feed system with adhesive transferred from a roll of tape.
A further feature of the invention is that the reinforcer application mechanism is extremely simple in construction. Unlike conventional combination hole punchers and reinforcers, the present invention does not require any elaborate, relative complex, and expensive tape feed mechanisms. To the contrary, the only mechanism that is required for applying reinforcement about the circumference of the holes as they are punched through the sheet material is a die punch upon which the flat reinforcement rings are stacked one atop another between a broadened punching tip located at the lower extremity of the die punch shank and a pressure plate locate above the stack of reinforcement rings.
The reinforcement rings are typically constructed as flat, annular rings having a circular outer periphery and a central opening therethrough, also circular in shape. The rings are stacked one above another and have pressure-sensitive adhesive on their lower faces and an adhesive-resistant coating on their upper faces.
Preferably, the die punch is comprised of a disposable punch and ring carrier magazine mechanism that is detachable from the lower end of a punching ram. The upper extremity of the detachable die punch and magazine may be screwed onto or otherwise removably attached to the lower end of a ram that moves through a laterally constraining guide. A plurality of reinforcement rings are stacked, on atop another, between a flat pressure plate disposed atop the shank of the die punch and magazine structure and the punching tip of the die punch. The reinforcement rings rest upon the shoulder that exists at the transition between the die punch magazine shank and the slightly broadened die punch tip. With the operation of the punch actuating lever the ram is forced downwardly. The pressure plate of the die punch presses the stack of reinforcement rings downwardly from above. Since the undersurfaces of the reinforcement rings are coated with pressure-sensitive adhesive, the sticky undersurface of the lowermost reinforcement ring is pressed against a sheet of material, such as paper, through which the slightly broadened die punch tip has just been forced.
The broadened die punch tip creates a hole through the sheet of paper, while the lowermost reinforcement ring is pressed against the upper surface of the sheet of paper. The punch ram is normally spring biased upwardly, so that when the operating lever is released, the ram is retracted upwardly, drawing with it the die punch magazine. Even though the broadened punching tip of the reinforcer magazine is slightly larger in diameter than the circular, inner circumference of the lowermost reinforcement ring, the reinforcement ring is sufficiently flexible so that it yields at its inner circumference to allow the slightly larger diameter punching tip to pass upwardly through its central opening.
The force of adhesion between the pressure-sensitive adhesive on the undersurface of the lowermost reinforcement ring and the upper surface of the paper surrounding the hole punched is sufficient to prevent the reinforcement ring from being lifted upwardly with the punching tip. However, since the upper surface of the reinforcement rings are treated so as to be resistant to adhesive, the adhesive bond between the undersurface of the reinforcement ring directly above the lowermost reinforcement ring and the upper surface of the lowermost reinforcement ring is quite weak. Consequently, as the punching tip is retracted upwardly through the central opening of the lowermost reinforcement ring, the weak bond between the upper surface of the lowermost reinforcement ring and the undersurface of the reinforcement ring located immediately thereabove is broken. The reinforcement ring located immediately above the lowermost ring, as well as all the rings stacked above that ring, are drawn upwardly clear of the lowermost ring and clear of the sheet of paper to which the lowermost ring remains attached.
With each operation of the punch and reinforcement mechanism, the reinforcement ring left at the bottom of the stack with the retraction of the punching ram becomes the lowermost ring and is then attached to the upper surface of another sheet of paper with the next sequential operation of the ram. Once all of the reinforcement rings have been applied to sheets of paper, or other material about the holes punched therein, the combination die punch and ring magazine is discarded.
Preferably, the detachable die punch is formed of an inexpensive, disposable material, such as hard plastic. It must be hard enough so that its punching tip is sharp enough to sever chads from paper or other sheet material. The reinforcement rings may also be formed of plastic, such a polyethylene terephthalate (PET). Preferably also, the upper surface of the reinforcement ring is made adhesive resistant by the application of a silicone layer. The undersurface of the PET reinforcement ring is coated with a conventional, pressure-sensitive adhesive of the type utilized on postage stamps, filing labels, and other types of articles which are secured to flat surfaces by pressure-sensitive adhesive.
In one broad aspect the present invention may be considered to be a punching and reinforcement apparatus for a combination hole puncher and reinforcer for punching holes in sheets of material and for concurrently applying reinforcement to those sheets of material about the holes therein. The invention is a lower die punch member having a transverse pressure plate with a cylindrical shank depending therefrom and a stack of reinforcement rings disposed on the cylindrical shank. Each reinforcement ring has an undersurface coated with a pressure-sensitive adhesive and an adhesive resistant upper surface.
The punching tip of the die punch has a sharp, cutting edge that severs a circular chad from a sheet of paper or other sheet material positioned therebeneath. The die punch tip can be constructed to have the same diameter as the shank. Ideally, since a weak adhesive bond exists between the upper surface of the lowermost reinforcement ring, and between all other reinforcement rings in the stack located thereabove, a stack of reinforcement rings may stay intact, releasing only the lowermost ring as its adhesive coated surface is pressed against the surface of the paper or other sheet of material to be punched and reinforced. As the lowermost ring is pressed against the sheet of material, the relatively strong bond between the adhesive coating on the underside of the lowermost ring and the sheet of paper is greater than the relatively weak bond between the undersurface of the reinforcement ring located immediately thereabove and the upper surface of the lowermost reinforcement ring. Consequently, the lowermost ring is left attached to the sheet of paper, while all reinforcement rings above the lowermost ring are lifted upwardly as the die punch is withdrawn from the paper.
As a practical matter, however, it is likely that some of the weak bonds between rings in the stack will fail, and some of the reinforcement rings may drop off the punching tip of the die punch if the punching tip has the same diameter as the die punch shank. Therefore, in a preferred construction, the die punch tip has a somewhat greater cross-sectional area than the shank above it and a slightly greater diameter than the openings through the reinforcement rings. Consequently, the shoulder formed at the transition between the die punch tip and the die punch shank prevents the reinforcement rings from dropping off of the lower end of the die punch.
In a preferred embodiment of the invention, the lower die punch member is comprised of a transverse pressure plate located atop a cylindrical shank that depends therefrom. The stack of reinforcement rings is disposed on the cylindrical shank. Preferably, the cross-sectional area of the punching tip is slightly greater than that of the shank and an upwardly inclined shoulder is formed at the demarcation between the punching tip and the shank. The shoulder may be formed with a frustoconical surface having a sloping angle of between about ten degrees and about twenty degrees relative to the vertical axis of the die punch shank. In a preferred construction in which the diameter of the openings in the reinforcement rings is six or seven millimeters, the slope of the frustoconical surface of the shoulder at the transition between the shank and the punching tip is fourteen degrees, two minutes, and the diameter of the punching tip is between 0.05 and about 1.00 millimeters greater than the diameter of the shank. The diameter of the die punch shank should be between about 0.05 and about one-half millimeter less than the diameter of the opening through the reinforcement rings mounted upon it.
Each reinforcement ring is preferably constructed as a flat, circular, annular disc of polyethylene terephthalate (PET) having a circular outer diameter of fourteen and a half millimeters and a circular, central aperture therethrough of six or seven millimeters. Each PET ring is preferably about 0.05 millimeters in thickness.
Preferably the lower surface of each of the reinforcement rings has a plurality of raised protrusions thereon, which may be formed of polypropylene (PP). These protrusions serve as spacers to reduce the extent to which the adhesive coating on the underside of the reinforcement rings is forced into intimate contact with the sprayed silicone coating on the upper side of the reinforcement ring located immediately therebeneath. These protrusions may be formed as a plurality of linearly extending, raised ribs that intersect each other in a right-angles to delineate a square grid.
In another aspect the invention may also be considered to be an improvement in a combination hole punching and reinforcing device for punching holes in sheets of material using a die punch and for concurrently reinforcing the sheets of material about the holes therein. According to the improvement of the invention the die punch is configured with a punching tip at its lower extremity and a shank narrower than the punching tip projecting upwardly therefrom, and a transverse pressure plate located on the shank. The invention also includes reinforcement rings that have central openings therethrough slightly smaller than the punching tip. The reinforcement rings have undersurfaces coated with pressure-sensitive adhesive. The reinforcement rings are carried by the shank stacked beneath the pressure plate and above the punching tip for sequential application to the sheets of material.
In still another aspect the invention may be considered to be a combination hole puncher and reinforcer comprising: a base, a pair of stanchions projecting upwardly from the base, vertical guides mounted on each of the stanchions, a separate punching ram mounted in each of the guides, an operating lever coupled to the punching rams, a die punch for each of the rams, each die punch having a shank with a broadened tip at its lower extremity, and a transverse pressure plate located on the shank of each die punch above the broadened tip thereof. A plurality of annular reinforcement rings are mounted atop the die punching tip shanks of the die punches between the broadened lips and the transverse pressure plates.
The base has a flat upper surface with a pair of die-receiving openings defined therein. The stanchions form edge stops for positioning a sheet of material on the flat upper surface of the base. The vertical guides are mounted vertically above the die-receiving openings in the flat upper surface of the base and are laterally displaced from the edge stops.
The punching rams each have a lower end mounted in each of the guides and laterally constrained by the guides. The operating lever has a fulcrum axis at the stanchions that is parallel to the flat upper surface of the base. The operating lever moves the punching rams together in vertical reciprocation within the guides.
The die punches are preferably detachably attached to the lower ends of the punching rams. The broadened tips fit closely within the die-receiving openings in the upper surface of the base. The transverse pressure plates are located on the shanks of the die punches and above the broadened tips thereof. The upper surfaces of the pressure plates may be provided with releaseable couplings, such as threaded studs, that engage the lower ends of the punching rams.
The reinforcement rings each have a central opening therethrough that is of a cross-sectional area slightly less than that of the broadened tips of the die punches and slightly greater than that of the die punch shanks. Each reinforcement ring has an undersurface coated with a pressure-sensitive adhesive. The reinforcement rings are mounted on the die punch shanks between the broadened tips and the transverse pressure plates thereof.
The invention may be described with greater clarity and particularity by reference to the accompanying drawings.